Mine Safety and Health Administration (MSHA) - Report of ...

stipulation that this distance could be increased if conditions improved. However, both MSHA
and UEI had to agree on the increased distance prior to implementation. To limit the exposure of
workers inby supports, the RocProps were required to be set one at a time.
Another modification required three steel cables to be installed outside the RocProps instead of
the one cable previously required. The cables were to be installed at the top, middle, and bottom
of the supports. Each steel cable would wrap around a RocProp and be fastened to itself in
40-foot increments. Each cable was required to be connected to a separate RocProp and
terminated using three clamps.
Additional ventilation requirements were also stipulated in this modification. Permanent
ventilation controls were to replace the temporary controls inby crosscut 120. A handheld
detector was to be placed in the No. 3 entry on the return side of the door at crosscut 120 until an
atmospheric monitoring system oxygen sensor could be installed. Also, all shuttle car operators
were required to have an extra SCSR in the operator’s compartment at all times.
On August 11, 2007, Peacock reported that ground stress had migrated eastward and affected
pillars outby the Main West seals. MSHA examined the area and mapped these ground
conditions in the Main West entries and the North and South Barrier workings outby crosscut
119. Pillar damage was noted up to three crosscuts outby the seals, to near crosscut 115 (see
Figure 3). The damaged ribs were sloughed due to abutment stress from the area to the west. At
that time, it appeared that the ground stress had stabilized and was no longer progressing
eastward. Clean-up in the No. 1 entry had advanced near crosscut 124.
On August 12, roof deterioration was observed near crosscut 115 in the No. 1 entry. Steel
channels were installed for additional support in this area (see Figure 9). The channels were
supported on both ends with hardwood posts. At the time, clean-up in the No. 1 entry had
advanced just inby crosscut 124. The No. 1 entry was packed with rubble the full width and
height of the original mined opening. The continuous mining machine was loading from a
rubble pile that resembled an unmined coal face (see Figure 10 and Figure 11). Observations of
RocProps tilted from vertical prompted MSHA to install a measurement point to monitor
horizontal movement between crosscuts 123 and 124.
Figure 9 - Steel Channels Installed in No. 1 Entry to Support Deteriorated Roof
23